Apparently, the very people that make Wheaties don't feel that this is the case, or they would make more.  If there was sufficient demand for a low-priced alternative, they would white-label it and capture both markets.

What I'm trying to say is that your statement that there is a business opportunity here, appears to be contradicted by actual data and the actions by the very people that could fill the demand that you believe exists.

Maybe a cereal that tastes like a slightly sweetened cardboard box that gets soggy almost immediately when milk is out on it just doesn't have a whole lot of appeal.